1Certainly, surely, indeed — an adverb conceding or affirming that something is true. Used to agree with someone ('that's true'), to firmly confirm or stress a fact, and in the concessive pattern 確かに〜が… ('admittedly …, but …').
「この店、ちょっと高くない？」「確かに。でも味は本物だよ。」
"Isn't this place a bit pricey?" "True. But the food is the real deal."
確かに値段は高いが、その分だけ長く使える。
Admittedly it's expensive, but it lasts that much longer to make up for it.
書類は確かに受け取りました。ご確認ありがとうございます。
I have definitely received the documents. Thank you for confirming.
言われてみれば、確かにここに鍵を置いた覚えがある。
Now that you mention it, I do recall leaving the key here.
彼の指摘は確かに鋭く、反論のしようがなかった。
His point was certainly sharp; there was no way to argue back.